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vdubn 02-24-2006 08:48 PM

Eton 90 - No power off-idle
We have an Eton 90cc, and it has a new top end, and for some reason, has zero umph off idle. If you push it to get the wheel speed up, it runs awesome on the top end.

We have checked the piston (made sure it wasn't in backwards), checked the carb, totally clean, checked to make sure the flywheel key didn't shear and retard timing, etc. It fires up on the first kick, but literally can't go up any incline, no matter how slight, until the rpms come up. Its almost like something is loading it and won't allow it into its powerband.

Any help or referral to someone that could, would be greatly appreciated.

Also, the manual says to check the timing, does anyone know what the procedure is for checking the timing on one of these 90cc engines?


Spike99 02-25-2006 07:24 PM

Re: Eton 90 - No power off-idle

Sounds to me like a stuck roller in the CVT system.

Before we get into checking this, here's a few tests you might want to do.

1 - Check engine PSI. For a stock piston / head replacement, the PSI is probably around the 100-120 range. The Pred-90 is 120 PSI - fresh stock. Pred-90 normal PSI is 100. I'm sure the stock E-Ton 90 2 stoke is the same PSI range.

2 - Did you only change the piston / cylinder or did you also change the air filter system? If you changed the air filter system at the same time, you definately need to re-jet.

3 - Perform a "quick check" for proper jetting and low RPM Air Leaks. This can be done by looking at the spark plug color. It should be slight black to beer bottle brown at idle and at the 1/4 throttle range. Let the engine idle for 5 minutes and check its plug color. If it isn't within this color range, it could be an air leak, dirt in the carb or its air screw or lower size jet may need to be adjusted. If the plug is white or has white specs, stop running it. The engine is way too lean and thus, running too hot.

Note: To learn more about testing for air leaks (especially after upgrading a 2 stroke engine), surf:

4 - The problem you described is most often a stuck roller in the CVT system. Especially if it worked great before your engine re-build. To check for a stuck roller, you need to remove the CVT cover and remove the front clutch system. For more details and pictures of this area, surf:

Note: When testing a rebuilt engine, I've been told many times that it is recommended NOT to place the ATV on blocks and "punch its throttle". With no drag on its rear wheels, the CVT system revs "super fast" very quickly and sometimes, its CVT rollers get stuck. If testing on blocks, press the gas slow up to 1/2 throttle and let it rev down at its natural speed. Thus, the CVT system isn't "jerked above" its expected normal operating stess levels.

Hope this info helps...


jinbeilai 02-26-2006 02:27 AM

Re: Eton 90 - No power off-idle
It's my first time to join in these knowledgeful boards. Can learn more from here. Although I don't know how to do with these problems our fellows met with, I wish some messages posted by heartful people will be helpful.
Well done!


vdubn 02-26-2006 10:51 AM

Re: Eton 90 - No power off-idle
You are the man! It was a roller issue actually. I found out about an hour after we posted after looking at pictures of the CVT and knowing that the belt should be around the small diameter and move to the outer diameter as speed increases.

The belt was at the outer diameter all the time, so it was like it was starting in high gear.

Now the only issue we have is that it doesn't hit as hard as my other Eton 90. The other one will do wheelies, whereas this one revs a bit, then takes off. I figure it could use the lighter rollers, and a better variator (with the better ramp.. hopefully I am describing it correctly).

Do you guys have any recommendations for where to get a replacement variator with the correct ramp, and the rollers, etc.?

Thanks for all of your help!

Spike99 02-26-2006 04:45 PM

Re: Eton 90 - No power off-idle

For rollers, clutches and replated CVT part upgrades, contact:

Rich at
Billy at
Ed at
Brad (???) at

These guys have the answer and parts you are looking for...


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